A wash sink of sufficient size to permit complete immersion of utensils, with hot and cold running water and the necessary soap or washing powder, shall be installed for the washing of trays, utensils, and other equipment used in the market. Adequate protection to prevent splashing of the walls behind the sink shall be provided. Where no lavatory provisions are made for washing the hands, the wash sink shall be equipped with a combination faucet permitting the proper mixing of hot and cold running water, and the required soap and individual towels shall be furnished.